Sculpt tool wont work ( Red Cursor)
You need to click your object to active select (Yellow outline not orange) the object you want to sculpt in object mode. Any other selections(orange outline) will not be sculpted in sculpt mode. 

See here for more on selecting: https://docs.blender.org/manual/en/latest/scene_layout/object/selecting.html

You can change your shading mode in the upper right corner.